This invention relates to a watering system for a greenhouse. More particularly, this invention relates to an overhead sprinkler watering system for greenhouses.
Greenhouse watering system typically comprise a traveling carriage and a conveyance device for delivering water to the carriage from a remote water source. In most commercial automatic water sprinkling systems used in greenhouses today, the conveyance device includes a hose which lays in a trough or on a flat tray disposed alongside the travel path of the carriage and generally composed of synthetic resin material. The hose is dragged along the tray or trough by the carriage and is subjected to tension which varies, depending on the position of the carriage along it travel path and further depending on the portion of the hose under consideration. More particularly, that portion of the hose located at the carriage is subjected to tension varying from zero, when the carriage has just reversed its direction of movement, to a considerable amount, as the carriage approaches an end of its travel path. A major disadvantage of such a water sprinkling system is that reversing the direction of motion of the carriage before the carriage has reached the end limit of its travel path, i.e., before the hose is stretched to its fullest extent, creates kinks and tangles in the hose, with the possible additional result that the hose or a portion thereof is dislodged from the support tray. Accordingly, to avoid such kinks or tangles in the hose, the carriage must always travel to the ends of its path, even if those path ends do not extend over crops requiring water.
Further disadvantages of the above-described water sprinkling system are that the varying tension on the hose causes variations in the travel speed of the carriage, thereby varying the amount of water applied, and greatly stretches the hose, which periodically necessitates cutting of the hose and of any electrical wiring which may be contained therein. In addition, the friction between the hose and the tray increases the power consumption of the carriage driving machinery and results in a relatively rapid wearing of the hose material.
In another kind of automatic sprinkling system for greenhouses, the water delivery hose is alternately wound on and unwound from a spool or reel as a hosecar reciprocates along a rail or track. For example, U.S. Pat. No. 4,723,714 to Lucas discloses a programmable sprinkler system comprising a carriage or hosecar which travels alternately along each of a plurality of parallel overhead rails extending perpendicularly from a common rail. The hosecar is moved from one overhead rail to another by a carrier mechanism shiftably disposed on the common rail. The hosecar supports a reel housing upon which a hose is wound. The hose is connectable at one end to a valve located at the conjunction of the common rail and a respective overhead rail. As the hosecar travels outwardly from the common rail along an overhead rail, the hose is unwound from the reel housing.
U.S. Pat. No. 4,074,856 to Williams et al. also discloses a greenhouse watering apparatus wherein a rotary reel supported by a translating carriage reels in or unreels a flexible water delivery hose.
An automatic sprinkling system incorporating a hose reel, although desirable for some applications, has certain disadvantages in other applications. For example, because essentially the entire hose, together the reel and ancillary mechanisms, is supported by a sprinkling carriage, there are inherent limitations as to the distance which can be covered by the carriage and, consequently, restrictions on the sizes of the greenhouses in which the sprinkling system is utilizable.